There were three steps:

1. An online test about using and understanding algorithms. This is a pretty easy step.

2. A pair programming session with four tasks. This one took two hours, and we had to do and explain every step down to the lowest level.

The four tasks were to complete code samples regarding: cache implementation (with race conditions), downloading a resource (if not already in cache), serialization, and lastly, UIKit (some things regarding Auto Layout in code and UITableView).

This step is the real technical one, with medium difficulty, but it's hard because it's live action.

Also, the interviewer was really helpful; if you were stuck, he was always there to help. Bonus points for Revolut.

1. A final step: discussing with one of the Heads of Mobile Engineering for 30 minutes.

This one was the most intimidating. The interviewer had ADHD, was always moving, and was hard to follow.

He asked questions about testing, pull requests, code guidelines, and the hardest things to develop in UI and business.

Personally, this was the hardest interview of all. I felt I lost the position at this step, but thank God I haven't.

The hardest thing to implement regarding business logic.

One of the most complex views you implemented.